I came across this great piece of writing this evening from David Heinemeier at 37 Signals, who blogs with colleagues at signal vs noise. There's great content on the site, this included:

To truly be inspired for great work, you need to know that you’re making a difference. That you’re putting a meaningful dent in the universe. That you’re part of something that’s making a difference and that your role in that something is significant.

This doesn’t have to be grand at all. You don’t have to be looking for the cure for cancer. It could be done by a waitress at a neighborhood cafe that’s the gathering point of local artists. The key is that your efforts would be missed, your customers would have a sense of loss, if you stopped doing what you’re doing.

If you’re void that sense of purpose, the pleasure in your work will eventually wane and ultimately feel hollow. I’ve lived that sensation more than once. Working with tools and techniques and even people that I enjoyed, but where the end did not justify the journey.

You can only hide in shadows of the circumstantial for so long before your passion begins to fade. You can only excuse your lack of impact on the world with “but it’s great money” or “at least we’re doing agile” or even “this way I get to use Rails” until the playlist of stories repeat and it just all sounds the same.

Remember that your time is limited. By the time you discover that you’ve been coasting on empty calories, the pale face staring you back in the mirror might be hard to recognize.

I remember waking up to such a face on day long ago and thinking “the world would have been no different if I had not been here the past six months”. That’s a terrible feeling of regret.

But the good story is that it’s never too late to do something about it. I’d give up a cozy working atmosphere and using tools I enjoyed if it meant having to do work that just didn’t matter. You should too.